Solventborne and activated solventborne paint packs, and waterborne coating compositions containing them

ABSTRACT

A pigmented solventborne paint pack which can be made into a waterborne coating composition is provided, which comprises: i) a solution in an organic solvent of polymer having functional groups and hydrophilic groups; and ii) a waterborne pigment dispersion comprising pigment dispersed in water in the presence of a pigment dispersant, the aqueous pigment dispersion itself being in dispersion in the solution of i). Also provided is a solventborne activated paint pack comprising the paint pack described above and further comprising a crosslinker which is dissolved in the organic solvent. Further provided is a waterborne coating composition which comprises a dispersion in an aqueous medium of the solventborne activated paint pack.

REFERENCE TO RELATED APPLICATIONS

This patent application claims priority of GB 9828443.3 filed on Dec.24, 1998, which was also filed as PCT Application No. PCT/GB99/04375 onDec. 23, 1999, designating the United States of America.

FIELD OF THE INVENTION

This invention relates to a coating composition, certain intermediatecompositions in its preparation, a process for preparing the compositionand to the use of the composition in a coating process.

BACKGROUND

One significant market for paints is in the repainting of motor vehiclesafter crash damage repair or refurbishment. This is often referred to asVehicle Refinish. One of the most common types of vehicle refinishpaints currently on the market comprises a hydroxyl functional polymerand a polyisocyanate crosslinker in an organic solvent. Because thepolymer and the crosslinker react together from the time they are mixed,they are generally supplied to the end user as two separate componentswhich are mixed together shortly before use. For this reason, they areoften called “two-pack” paints.

In practice, the component containing the polymer also contains anycomponents such as pigments, fillers, extenders or other additives whichmay be required to give the paint its final colour or to modify itsproperties. Pigments or extenders are particulate materials which areheld in stable dispersion in the solventborne composition by a pigmentdispersant. In making the compositions, the pigments, fillers andextenders are usually firstly made into a pigment millbase. A pigmentmillbase is made by mixing the pigments, fillers and extenders and thepigment dispersant, usually with a little solvent, in a high shear mixersuch as a ball mill so as to thoroughly separate the pigment particlesand coat them with dispersant. The resulting millbase is then mixed withpolymer and solvent to form the composition known as the “paint pack” assold to the end user. The user then mixes this paint pack with asolution of the crosslinker in organic solvent, referred to as the“hardener”, just prior to use.

There is environmental and legislative pressure to reduce the emissionof organic solvents from coating compositions when they are applied anddried to form a paint film. One way to achieve this is to use waterbornecompositions.

Producing a waterborne equivalent of the vehicle refinish two pack paintdescribed above is not simply a question of replacing all of the solventwith water. Each component must be modified in order to make it watersoluble or dispersible. In particular, the modification wouldnecessarily involve the introduction of hydrophilic groups into thecrosslinker which must be made water dispersible. The introduction ofhydrophilic groups into the crosslinker has been found to make the finalpaint film more sensitive to water, rendering this route unattractive inproducing high performance refinish paints with good water resistance.

In an alternative (see EP-358979) the polymer is produced in an organicsolvent. On completion of the polymerisation reaction the organicsolvent is removed and the polymer and is made into an aqueous solutionor dispersion. Pigment may then be added to the aqueous polymer solutionor dispersion (if required) before addition of the isocyanatecrosslinkers.

It is however desired to obtain coatings having improved waterresistance compared to the water resistance of coatings produced inaccordance with EP-358979. This is achieved in accordance with thepresent invention by the use of a solution in an organic solvent ofpolymer having functional group and hydrophilic groups having dispersedtherein a waterborne pigment dispersion.

One proposed alternative method of producing a waterborne two packcomposition uses a solventborne paint pack. The polymer and thecrosslinker are both chosen to be soluble in an organic solvent and thepigment millbase is made using a pigment dispersant compatible with thesolvent. The polymer is dissolved and the pigment is dispersed in theorganic solvent to form the solventborne paint pack. The end userdissolves the crosslinker in the solventborne paint pack to form anactivated paint pack and then disperses this in water to form thewaterborne coating composition ready for use.

It has been found that this route can provide waterborne two packcompositions with equivalent performance to solventborne compositions.The problem with this route is that although the majority of the carrierfluid can be water, there is still a relatively high level of solventpresent from the solventborne paint pack. Levels of solvent inessentially waterborne compositions are often expressed as volatileorganic content (voc) in grams per liter of composition excluding water(g/l). For primer composition, these types of composition still have avoc in the region of 350 g/l. This is less than conventionalsolventborne primer compositions but existing and forthcomingregulations are aiming at 250 g/l, and a still lower level is clearlydesirable. For single layer topcoat compositions these types ofcomposition still have a voc in the region of 420 g/l, which again isless than conventional solventborne topcoat compositions but forthcomingregulations are aiming at 340 g/l, and a still lower level is clearlydesirable.

We have now discovered that it is possible to reduce the voc of thesetypes of composition by the use of a waterborne pigment millbase. Thiswaterborne millbase is dispersed in a solution of the polymer in anorganic solvent so as to form the paint pack. The polymer hashydrophilic groups so that it acts to stabilise the water-in-oilemulsion of the millbase in the polymer solution. It also has functionalgroups which will react with the crosslinker. A crosslinker is usedwhich is not hydrophilically modified and which is soluble in theorganic solvent. Just prior to use, the crosslinker is added to thisdispersion and dissolved in the solvent and then this mixture is finallydispersed in water. This oil-in-water dispersion is also stabilised bythe polymer. This method allows crosslinker without hydrophilic groupsto be used, while at the same time allowing compositions to be madehaving a volatile organic content significantly lower than those made byconventional routes.

SUMMARY OF THE INVENTION

According to the present invention there is provided a pigmentedsolventborne paint pack which can be made into a waterborne coatingcomposition which comprises;

-   i) a waterborne pigment dispersion, comprising pigment in dispersion    in water in the presence of a pigment dispersant, the waterborne    pigment dispersion itself being in dispersion in-   ii) a solution in an organic solvent of polymer having functional    groups and hydrophilic groups.

The present invention also provides a solventborne activated paint packwhich comprises the solventborne paint pack and a crosslinker which isdissolved in the organic solvent. The present invention also provides awaterborne coating composition which comprises a dispersion in anaqueous medium of the solventborne activated paint pack.

According to the present invention there is also provided a process forproducing a solventborne paint pack which can be made into a pigmentedwaterborne coating composition comprising a polymer having functionalgroups and hydrophilic groups and a crosslinker for the polymer,comprising the steps of;

-   i) forming a solution of the polymer in an organic solvent-   ii) dispersing a waterborne pigment dispersion in the polymer    solution.

The present invention also provides a process for producing asolventborne activated paint pack, which can be made into an aqueouscoating composition, comprising the further step of adding to thesolventborne paint pack a crosslinker which is soluble in the organicsolvent and forming a solution of the crosslinker in the solvent.

The present invention also provides a process for producing an aqueouscoating composition which comprises the further step of emulsifying thesolventborne activated paint pack in an aqueous medium.

DETAILED DESCRIPTION OF THE INVENTION

Organic solvents include any non-aqueous solvents which can be used todissolve the polymer and which have little or no solubility in water. Itcan be an aliphatic or aromatic hydrocarbon such as Solvesso 100™,toluene or xylene, an alcohol such as butanol or isopropanol, an estersuch as butyl acetate or ethyl acetate, a ketone such as acetone, methylisobutyl ketone or methyl ethyl ketone, an ether, an ether-alcohol or anether-ester or a mixture of any of these.

The polymer can be any polymer having functional groups and hydrophilicgroups and which can act to stabilise the dispersion of aqueous millbasein the polymer solution and which can stabilise the emulsion ofactivated paint pack in the aqueous phase.

Functional groups are groups which can react with a crosslinker so as tocrosslink the polymer in the final coating film. For example, thefunctional groups can be amine groups, hydroxyl groups, acetoacetategroups, silane groups, carboxylic acid groups or epoxy groups,preferably hydroxyl groups or epoxy groups and most preferably hydroxylgroups.

Examples of suitable hydrophilic groups are carboxylic acid groups andamine groups. When the hydrophilic groups are carboxylic acid groups,the polymer preferably has an acid value of 20 to 250. When thehydrophilic groups are amine groups, the polymer preferably has an aminevalue of 20 to 250. Preferably acid or amine groups on the polymer areat least partially neutralised and more preferably fully neutralised.For example, acid groups can be neutralised using a suitable base suchas ammonia or an amine such as dimethylethanolamine, and amine groupscan be neutralised using an acid such as lactic acid or acetic acid.When the hydrophilic groups are amine groups or carboxylic acid groups,they can also act as functional groups.

The polymer can be a vinyl addition polymer, a polyester, apolyurethane, a mixed polyester-polyurethane or an epoxy polymer,preferably a vinyl addition polymer, a polyester, a polyurethane or amixed polyester-polyurethane and most preferably a vinyl additionpolymer.

Preferred polymers have a number average molecular weight as measured bygel permeation chromatography of 700 to 10,000, more preferably 1,000 to4,000. Preferably, when the polymer has hydroxyl groups, it has ahydroxyl value of 5 to 500, more preferably 50 to 250.

Preferred polymers have an acid value (AV) of up to 50. Acid value isthe mass of potassium hydroxide in milligrams required to neutralize theacid groups in 1 gram of solid resin.

Suitable polyesters are derived from a polybasic acid and a polyhydroxycompound and are generally hydroxyl functional.

Polybasic acids are compounds having two or more carboxylic acid groups.Such polybasic acids are well known in the polyester art. Examples ofsuitable polybasic acids are C₁₋₆ alkane dioic acids such as succinicacid, glutaric acid, adipic acid or hexanedioic acid, cycloaliphaticacids such as hexahydrophthalic acid, unsaturated alkane dioic acidssuch as fumaric or maleic acids, dimer acids, and aromatic acids such aphthalic acid, isophthalic acid and trimellitic acid. Ester-formingderivatives of such acids can also be used in place of the free acids.Ester-forming derivatives include anhydrides and lower alkyl, forexample methyl or ethyl, esters. Mixtures of two or more acids or theirester-forming derivatives can be used.

Polyhydroxy compounds are compounds having two or more hydroxyl groupsand are well known in the polyester art. Examples of suitablepolyhydroxy compounds are diols such as ethylene glycol, propyleneglycol, 1,3-propane diol, butylene glycol, 1,4-butane diol, 1,6-hexanediol, neopentyl glycol, triols such as trimethylol propane, andglycerol, tetrols such as pentaerythritol and higher polyols such assorbitol. Mixtures of two or more of these polyols can be used.

Polyurethanes or mixed polyester-polyurethanes can be made in a similarway to polyesters but using a di- or polyisocyanate instead of some orall of the polybasic acid. They are generally hydroxyl functional.Suitable diisocyanates are tetramethylxylene diisocyanate, hexamethylenediisocyanate, isophorone diisocyanate and toluene diisocyanate. Suitablepolyisocyanates include the isocyanurate trimers, allopanates anduretdiones of diisocyanates such as those described above as well as thereaction products of these diisocyanates with polyols. Polyols arecompounds having two or more hydroxyl groups. Suitable polyols includetrimethylol propane, glycerol and pentaerythritol. Many suchpolyisocyanates are commercially available, for example under theDesmodur trade mark from Bayer or the Tolonate trade mark from Rhodia.

The polyester, polyurethane or polyester-polyurethane can be made byconventional means. Generally the components of the polyester are meltedtogether or dissolved in a suitable solvent, such as xylene. The melt orsolution is then heated so as to remove the water produced in thereaction between the acid and the hydroxyl groups. When the componentsare melted together, the water can conveniently be removed using afractionating column at temperatures of between 150 and 250° C. When thecomponents are dissolved in a solvent the water can conveniently beremoved by azeotropic distillation using a Dean and Stark apparatus atthe reflux temperature of the solvent. A combination of these method canbe used, initially melting the components together and removing waterusing a fractionating column and then adding solvent and removingfurther water using a Dean & Stark apparatus. If a polyisocyanate is tobe included to produce a polyester-polyurethane, then this is generallyadded after reaction of the other components, and at a lowertemperature, such as between 50 and 100° C. because the isocyanategroups are much more reactive than acid or ester groups.

Acrylic addition polymers are derived from polymerisable ethylenicallyunsaturated monomers such as vinyl or acrylic monomers and comprisefunctional units, hydrophilic units and structural units. Wheneverreferred to herein, the term acrylic monomer refers to esters of acrylicor methacrylic acid. The term (meth) acrylate refers to both theacrylate and methacrylate equally and the term (meth) acrylic acidrefers to acrylic or methacrylic acid equally.

Functional units are derived from vinyl or acrylic monomers which havefunctional groups on them. For example, glycidyl methacrylate can beused to produce a polymer having epoxy functional groups and aminoethylmethacrylate can be used to produce a polymer having amine functionalgroups. Polymers having hydroxyl functional groups can be made usinghydroxyl functional vinyl or acrylic monomers. An example of a hydroxylfunctional vinyl monomer is vinyl alcohol. Examples of hydroxylfunctional acrylic monomers are hydroxy ethyl (meth) acrylate, hydroxybutyl (meth) acrylate and hydroxy propyl (meth) acrylate.

Other examples of suitable hydroxyl functional monomers are the reactionproducts of glycidyl (meth) acrylate with mono-carboxylic acids, such asversatic acid and the reaction product of (meth) acrylic acid withmonoepoxy compounds such as Cardura E™ (the glycidyl ester of versaticacid; from Shell).

Hydrophilic units are derived from monomers having hydrophilic groups.Examples of monomers having hydrophilic groups are acid functionalmonomers, such as acrylic acid and methacrylic acid, and aminefunctional monomers such as dimethylaminoethyl acrylate.

Structural units are derived from monomers which do not have anyfunctional groups which will react with the crosslinker nor anyhydrophilic groups. Examples monomers from which the structural unitscan be derived are non-functional vinyl monomers and alkyl esters of(meth) acrylic acid.

Examples of suitable non-functional vinyl monomers are styrene, tertiarybutyl styrene and alphamethyl styrene, preferably alphamethyl styrene.Examples of suitable alkyl esters of (meth) acrylic acid are C₁₋₁₂ alkylesters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl(meth) acrylate, t-butyl (meth) acrylate, n-propyl (meth) acrylate andisobornyl (meth)acrylate.

Molecular weight regulators such as mercapto compounds, for examplen-ctyl mercaptan, can also be added to control molecular weight.

Preferred acrylic addition polymers have a theoretical glass transitiontemperature (Fox Tg) of −30 to 80° C., more preferably −10 to 50° C.

Many suitable acrylic addition polymers are commercially available. Theycan also be produced by conventional means. The acrylic addition polymercan be produced by contacting a mixture of the appropriate monomers witha polymerisation initiator at a temperature at which polymerisationoccurs. For example the monomer mixture can be slowly fed into asolution of initiator held at the polymerisation temperature or theinitiator can be fed into a solvent at the polymerisation temperaturesimultaneously with the monomer mixture.

Suitable initiators are azo initiators such as azodiisobutyronitrile and2,2′ azobis (2-methylbutyronitrile) or peroxy initiators such as benzoylperoxide.

The pigment is dispersed in water using a suitable pigment dispersant. Asuitable pigment dispersant is Dispex GA40™.

The term pigment includes fillers and extenders as well as conventionalpigments. Pigments are particulate materials which impart colour oropacity to the final paint film. Extenders and fillers are usuallyinorganic materials which can be used to reduce the cost of aformulation or to modify its properties. In particular, fillers andextenders can be used in primers to improve their ability to hide minorsurface imperfections and also to make them easier to rub down withsandpaper to provide a smooth surface for subsequent topcoatapplication. We have found that the process of the present invention isparticularly beneficial in the production of primers because theycontain a relatively high level of pigment and so the reduction in vocachieved by this process is particularly marked. Crosslinkers arecompounds which react with at least two functional groups on the polymerso as to crosslink the composition. When the functional groups arecarboxylic acid groups an example of a suitable crosslinker is acarbodiimide. When the functional groups are amine groups, examples ofsuitable crosslinkers are polyepoxides and polyisocyanates. When thefunctional groups are epoxy groups, examples of suitable crosslinkersare polyamines. When the functional groups on the polymer are hydroxylgroups, examples of suitable crosslinkers are phenol formaldehydes,melamine formaldehydes and polyisocyanates.

Polyisocyanates are preferred crosslinkers. Polyisocyanates arecompounds having two or more isocyanate groups per molecule and are wellknown in the coatings art. The isocyanate groups can be blocked butunblocked isocyanates are preferred.

Suitable diisocyanates are tetramethylxylene diisocyanate, hexamethylenediisocyanate, toluene diisocyanate and isophorone diisocyanate.Preferably, the polyisocyanate has an isocyanate functionality of 2.5 ormore isocyanate groups per molecule. Suitable polyisocyanates of thiskind include the isocyanurate trimers, allophanates and uretdiones ofdiisocyanates such as those described above as well as the reactionproducts of these diisocyanates with polyols. Polyols are compoundshaving three or more hydroxyl groups. Suitable polyols includetrimethylol propane, glycerol and pentaerythritol. Many suchpolyisocyanates are commercially available, for example under theDesmodur trade mark from Bayer or the Tolonate trade mark from Rhodia.

The aqueous medium comprises at least 50% by weight water, preferably atleast 90% and most preferably substantially all, for example 99.5%,water. The other components of the aqueous medium can be water miscibleorganic solvents.

The compositions can also contain catalysts for the reaction between thefunctional groups on the polymer and the crosslinker. For example,suitable catalysts for the isocyanate-hydroxyl reaction include tincatalysts such as dibutyl tin dilaurate and amine catalysts such astriethylamine. The compositions can also contain other conventionalpaint additives such as, pigments, fillers, UV absorbers and flow aids.

The solution of polymer can be made either by making the polymer inorganic solvent or by simple stirring of the polymer with the organicsolvent.

The pigment millbase can be made by mixing the pigments, fillers andextenders and the pigment dispersant, optionally with some water in ahigh shear mixer such as a ball mill, or a high speed rotary disperserso as to thoroughly separate the pigment particles and coat them withdispersant.

The crosslinker can be dissolved in the organic solvent by mixing, forexample by stirring.

The solventborne mixture of polymer, crosslinker and dispersedwaterborne millbase can be dispersed in the aqueous medium by stirring.

The coating composition of the invention can be applied to the surfaceof a substrate and then allowed or caused to dry and cure. According tothe present invention there is provided a process for coating asubstrate which comprises the steps of applying a layer of a coatingcomposition according to the present invention to a surface of thesubstrate and thereafter causing or allowing the layer to cure.

The coating composition can be applied by conventional means such as bybrush, roller or spray, preferably spray. The substrate can be forexample, metal, plastic, wood or glass. The compositions areparticularly useful for refinishing motor vehicles when they can be usedas topcoats although they are especially useful as primers.

The applied layer can be allowed to cure at ambient temperature in thecase where the polymer and crosslinker react together at ambienttemperatures. Alternatively the layer can be baked at elevatedtemperatures, for example 5°-120° C. to accelerate curing. Drying andcuring typically takes between 5 minutes and 24 hours depending on theambient conditions and on the particular components used. Convenientlyit takes about 15 minutes to about 5 hours.

According to the present invention there is also provided a coatedarticle obtainable by the process.

The invention will now be illustrated by means of the following examplesin which all parts are by weight.

EXAMPLES

1. Waterborne Pigment Millbase.

A dispersant (Dispex GA40™, 2.991 parts), antifoaming agent (SynperionicDF210™, 0.300 parts) and water (11.762 parts) were mixed together andput into a high speed disperser. The disperser was turned on and zincoxide (2.054 parts), zinc phosphate (14.266 parts), talc (24.414 parts),calcium carbonate (16.270 parts), titanium dioxide (Tipure R960-09™,21.563 parts) and Organic Black dispersion (Sandosperse™, 0.498 partswere added steadily so as to avoid the formation of lumps. Water (5.882)was added with the pigment to maintain a fluid mixture. High speedstirring was continued for 45 to 60 minutes. Mixing was continued for afurther 5 minutes.

Hydroxyl Functional Acrylic Polymer

A mixture of alpha methyl styrene (6.65 parts), tertiary butyl acrylate(19.96 parts), hydroxybutyl acrylate (19.16 parts), butyl acrylate(11.99 parts), acrylic acid (2.14 parts), azidiisobutyronitrile (Vazo67™, 2.57 parts), n-octyl mercaptan (2.33 parts) and butyl acetate 7.18parts) were slowly added to a mixture of butyl acetate (21.14 parts andalpha methyl styrene (6.65 parts) over 180 minutes at a temperature of135° C. The mixture was held at 135° C. for 15 minutes and then furtherinitiator (Triganox 21S™, 0.115 parts) was added. The mixture wasstirred for a further 60 minutes and then further initiator (Triganox21S™, 0.115 parts) was added. The mixture was held at 135° C. for afurther 60 minutes before being allowed to cool. The hydroxyl functionalpolymer had an acid value of 28.

3. Pigmented Paint Pack

A mixture of dimethylaminoethanol (0.57 parts) and water (5.16 parts)was added to the polymer solution produced in 2 above (15.77 parts).This mixture was added to the pigment millbase prepared in 1 above(73.87 parts) with stirring followed by butyl acetate (4.57 parts), anddibutyl tin dilaurate catalyst (0.06 parts).

4. Primer Compositions.

Three primer compositions according to the invention were made withthree different polyisocyanate hardeners. The components are set out inTable 1 below;

Polyisocyanate Pigmented Composition Hardener Paint Pack Hardener Water1 Tolonate HDT90 50 3.05 5 2 Desmodur Z4470 50 5.15 7.1 3 Cythane 317450 5.8 75. Comparative Tests

Two primer compositions were made, composition 4 according to theinvention and comparative composition 5 using hydrophilically modifiedpolyisocyanates which was added to the aqueous composition after mixingof the millbase and water. These compositions used the pigmented paintpack from 3 above (300 parts). For composition 4, a non-hydrophilicallymodified polyisocyanate, Cythane 3174™ (34.8 parts) was added to thepaint pack with stirring and then water (43.8 parts) was added withstirring to give the final paint composition 4. For comparativecomposition 5, water (43.8 parts) was added to the paint pack and then ahydrophilically modified polyisocyanate Desmodur VPLS 2032™ (39.6 parts)was added with stirring.

These primer compositions were applied by spray to steel panels to givea dry film thickness of 80 microns in three coats. The panels were leftfor 24 hours at ambient temperature (about 20° C.) to dry and cure.

The dried primer coatings were sanded to a smooth finish with P300 paperand a mechanical sander, and then topcoated with a commercial blacktwo-pack polyurethane topcoat. This was allowed to dry at ambienttemperature for 1 hour and then stoved for 30 minutes at 60° C.

The primed and topcoated panels were tested for Konig hardness andWatersoak Resistance. Watersoak Resistance is measured according to SMMT(Society of Motor Manufacturers Test) number 57. The results were asfollows;

Appearance SMMT Watersoak Adhesion Primer 4 Smooth & Glossy 8M 33Comparative Glossy with Pinholes 8VD 1 Primer 5

The Watersoak Resistance test result indicates the blistering of thepaint after 3 days. M means Medium blisters and VD means Very Denseblisters. The blister size of 8 is on a scale of 1 to 10 where 1 is 10nm and 10 is microscopic. Adhesion indicates the percentage of coatingremaining intact after applying sticky tape to the tested topcoat andremoving it.

This Watersoak Resistance test very clearly shows the benefit of theprocess and composition according to the invention which avoids the needfor hydrophilically modified polyisocyanates while giving a much lowervoc than is achievable by using known solventborne millbases inconjunction with non-hydrophilically modified polyisocyanates.

6. Topcoat Composition.

A white topcoat according to the invention was prepared as follows.

White Waterborne Pigment Millbase.

A dispersant (Dispex GA40™, 26.5 parts), antifoaming agent (SynperionicDF210™, 9 parts), polypropylene glycol (100.0 parts) and water (150.0parts) were mixed together and put into a high speed disperser. Thedisperser was turned on and titanium dioxide (Tipure R960-09™, 1393.0parts) was added steadily so as to avoid the formation of lumps. Water(183.0 parts) was added with the pigment to maintain a fluid mixture.High speed stirring was continued for 45 to 60 minutes. Mixing wascontinued for a further 5 minutes.

White Pigmented Paint Pack

A 10% aqueous solution of dimethylaminoethanol (7 parts) was added tothe polymer solution produced in 2 above (200.00 parts). This mixturewas added to the white pigment prepared above (190.0 parts) withstirring followed by butyl acetate (20 parts), and dibutyl tin dilauratecatalyst (0.25 parts).

White Topcoat Composition.

A white topcoat was made by mixing the paint pack prepared as above (164parts), a polyisocyanate (Cythane 3174™, 46.0 parts), a 10% aqueoussolution of dimethylaminoethanol (14.0 parts) and water (200.0 parts).

Application and Testing

The paint was allowed to stand for 30 minutes after mixing to give a lowviscosity composition suitable for spraying. The composition was sprayedonto a primed steel panel at a 40 micometer dry film thickness. It wasleft to dry for 1 hour at ambient temperature (about 20° C.) and thenstoved for 30 minutes at 60° C.

The resulting topcoat was smooth, glossy and defect free with a gloss of70 at 20 degree angle and a Koenig hardness of 53.

1. A coating composition comprising: (a) a pigmented solventborne paintpack comprising a water-in-oil emulsion comprising: i) a solution in anorganic solvent of a polymer having functional groups and hydrophilicgroups; and ii) a waterborne pigment dispersion comprising pigmentdispersed in water in the presence of a pigment dispersant, the aqueouspigment dispersion itself being in dispersion in said solution i), and(b) an aqueous phase, wherein the pigmented solventborne paint pack isdispersed in the aqueous phase.
 2. The coating composition of claim 1 inwhich the functional groups are hydroxyl groups.
 3. The coatingcomposition of claim 2 in which the polymer has a hydroxyl value of 5 to500.
 4. The coatina composition of claim 3 in which the polymer has ahydroxyl value of 50 to
 250. 5. The coating composition of claim 1 inwhich the hydrophilic groups are carboxylic acid groups or amine groups.6. The coating composition of claim 5 in which the hydrophilic groupsare carboxylic acid groups and the polymer has an acid value of 20 to250.
 7. The coating composition of claim 5 in which the hydrophilicgroups are amine groups and the polymer has an amine value of 20 to 250.8. The coating composition of claim 1 in which the polymer is a vinyladdition polymer, a polyester, a polyurethane, a mixedpolyester-polyurethane or an epoxy polymer.
 9. The coating compositionof claim 8 in which the polymer is a vinyl addition polymer, apolyester, a polyurethane or a mixed polyester-polyurethane.
 10. Thecoating composition of claim 9 in which the polymer is a vinyl additionpolymer.
 11. The coating composition of claim 10 in which the polymerhas a theoretical glass transition temperature (Fox T_(g)) of −30 to 80°C.
 12. The coating composition of claim 11 in which the polymer has atheoretical glass transition temperature (Fox T_(g)) of −10 to 50° C.13. The coating composition of claim 1 in which the polymer has a numberaverage molecular weight as measured by gel permeation chromatography of700 to 10,000.
 14. The coating composition of claim 13 in which thepolymer has a number average molecular weight of 1,000 to 4,000.
 15. Thecoating composition of claim 1 in which the polymer has an acid value ofup to
 50. 16. A coatina composition comprising: (a) a pigmentedsolventborne activated paint pack comprising a water-in-oil emulsioncomprising: i) a solution in an organic solvent of a polymer havingfunctional groups and hydrophilic groups; ii) a waterborne pigmentdispersion comprising pigment dispersed in water in the presence of apigment dispersant, the aqueous pigment dispersion itself being indispersion in said solution i); and iii) a crosslinker which isdissolved in the organic solvent; and (b) an aqueous phase; wherein thepigmented solventborne activated paint pack is dispersed in the aqueousphase.
 17. The coating composition of claim 16 in which the crosslinkeris a phenol formaldehyde, melamine formaldehyde, or polyisocyanate. 18.The coating composition of claim 17 in which the crosslinker is apolyisocyanate.